Spinning device



g- 1952 E. L. GRIGGS, JR., ET AL 2,605,555

SPINNING DEVICE Filed Oct. 11, 1949 2 SHEETS-SHEET 1 INVENTORS EKNESTLEEGRIGGSJP- (MIEE'MRYFOLGE'R 7211 1, 0

A T T OR/VEY g- 1952 E. L. GRIGGS, JR, ET AL 2,605,555

SPINNING DEVICE Filed Oct. 11, 1949 2 SHEETSSHEET 2 INVENTORS ERNEST LEEGRIGGS JR. amZJEME'RYFOL GER TAYLOR.

ATTORNEY Patented Aug. 5, 1952 IS-PINNQ ING DEVICE Ernest Lee Griggs,Jr., Waynesboro, and Emery Folger Taylor, Staunton, Va.,assignors to E.I. du Pont de Nemours & Company, Wilmington, DeL, a. corporation ofDelaware Application October ll, 1949, Serial No. 120,742

filaments from solutions of filament-forming materials bythedry-spinning or evaporative method.

In the conventional method for spinning filaments, as, for example, inusing a volatile solvent and a cellulose ester or ether, the solution isextruded under considerable pressure through a spinneret provided with aplurality of orifices into a heated enclosure generally called aspinning cell. An evaporative gaseousmedium, for example, air, is passedthrough the spinning cell either co-currently or countercurrently toremove volatile solvents from the formed filaments. I The filaments arethen collected as a yarn of the desired denier in the usual manner. Ithas been customary to employ, particularly in the case of co-current airflow, a slot or hole in a cone-type enclosure at the bottom of thespinning cell for filament exit. Somewhat prior to passing through theslot or aperture, the filaments pass an aspiration screen through whichthe solvent-laden air is withdrawn from the spinning cell and sent tothe solvent recovery system. The downward vertical flow of the airor'other evaporative medium is thereby altered abruptly. In many casesthe change may amount to 90. In the area of sudden change in flowdirection considerable turbulence occurs. This, of course, isdetrimental, for it leads to broken filaments and yarns of inieriorquality. In addition to the turbulence, a fpumping action is set up, andan appreciable amount of solvent-laden air is carried out into theatmosphere. Not only is thiseconomically wasteful, particularly in viewof the progressively higher losses being experienced with increasedspinning speeds, but it is a health hazard.

Filaments are also ofttimes led from the spin- --area.- In suchapparatus, however, the fila- 9 Claims. (01. 34-82) ments are drawn'from the'cell at right angles to the normal and are thereby placedunder undue tension resulting in inferior .articles of manufacture.Furthermore, there is a tendency for the downward'fiowing stream of airin the tube to carry the filaments beyond the side exit'point. Nosatisfactory apparatus has heretofore been designed which simultaneouslyreducesair turbulence in the thread path :within the cell and minimizesthe dragging of solvent-laden air into the spinning room. It hasindeedlongbeenxa' desideratum in the field ofv dry-spinning to'have anapparatus designed so thatthe take-ofif for the solvent-laden air is sosituated with respect to the thread exit point and of such-a shape thatlittlei'if any, solvent-laden airis dragged intothe spinning area.

It is an objectfofthis invention to. provide an improved apparatus ofsimple constructionadapted for use withthe usual type 'of' dry-spinningcell, whereby the aspiration take-off is placed adjacent to the filament'exit and arranged in such a manner that the' evaporative medium sweepsacross the-downwardly flowing filaments as they are positioned togetherby the sides of the exit aperture or by guides positioned just prior totheir exit fromthe cell." Another object of the present invention is toreduce'the turbulence of the evaporative medium inthe filament pathwithin the cell without interfering with the convenient operation of thespinning cell. A

further object is to reduce substantially the quantity'of solvent beinglost from the cell enclosure. A more specific object of the invention isto employ a throat insert or any restricted cross sectional arrangementto realize improved solvent recovery. A further object is topermit theyarn to leave the spinning/cell enclosure through an aperture withoutbeing deflectedfrom its normal downward path. A still further object istoprovide a screen access door or fluff trap arrangement which iscapable of being readily visible and easily removable for cleaningwithout interrupting the spinning. Another objective is toseparate atraveling filament or the like from a fluid surrounding it. Stillfurther objectsareto'minimize fire andhealth risks involved in thedry-spinning process, and-to provide an effective meansfor keepingyarn,broken filaments and spinning dope from passing into the solventrecovery system. Other objects of the invention will appear hereinafter.Y

The above objects of this invention are accom- "plished by the provisionof an aspiration take-off device positioned adjacent to 'theifilamentexit tion header and solvent recovery system. The

throat insert tends to increase further the air velocity across thefilaments at the narrowest point of the cell, thereby giving a suctioneffect in addition to the suction being applied by the solvent recoverysystem. The thread guide which I may be positioned close to the filamentexit permits the bundle of filaments to be centered'so that they maypass through the smallest allowable opening. I

The apparatus provides a means for separatingthe traveling filament-fromthe solution or vaporlsurrounding it as 'it passes through the deviceofthis invention; The apparatus comprises ahollow, preferably cylindrical.member, which is tapered somewhat atthe exit end and'in that end is asmall orifice for the exit of the filament.

Near'this orifice or joined to it is a guide which serves to keep thefilament running properly. Access to the orifice and guide is providedfor by a conveniently hinged door opening into the device. At thetapered end is a vent through which "the'vapor or solvent passes. Forbetter streamlining, ithis vent may extend below the filament exit butthis design is not required. The passageway between the tapered end "andthe vent'is 'made. much smaller than either that of the tapered sectionor vent in order to enhance the suc- "tion. through theifilament exitinto. the device.

This effect is. attained by providing in the vent a restrictioncontiguous with the tapered section. .Also in. the vent is a screen andthere is provided arr-access to this screen.

The'irrvention willsbe more easily understood by'reference to'thefollowing detailed description when taken in connection with theaccompanying illustrations in which Figure Us a sideelevational viewpartly in section showing the aspiration type spinning cone and the:exit door, taken on line l| of Figure 2, Figure-21s .a-plan view,online A A of Figure 1, showing the exit opening in more detail andFigure dis a perspectiveview of the apparatus of this invention showingthe exit door'and bot- .fiangesi. Any convenient of course, be used.

tom trap door inthe open position.

It :is'un'derstood that the following. description is given by way ofexample only and is in no respect limitative.

'Referring'to'Figure 1 the lower portionof the Withdrawn from the cellthrough aperture 1. Mounted in the device is a guide 9 for guiding thefilament or yarn through the exit. This guide could be placed in thedoor 8 if desired and a plurality of guides could also be used. In anyevent the guide is so built and positioned with respect to the" cellaperture Tth'at the-direction of air across the threa'din the cell tendsto hold the thread positioned in the guide. By means of throat insert llnear the tapered section l2 and in the vent E8 or the aspirationtake-off, a suction e'iiect supplementary to that being applied spinningcell l adjoins the aspiration'take-ofi exit door assembly 2. The celland the spinning device 2 of this-invention are attached by anyconvenient means. For example, gaskets 3 are used as seals andcap'screws l-are anchored in anchoring means may,

, 'The spinning cell may be heated in any desired manner-and is providedwith'means (not shown) for passing a drying and evaporative medium,

iii)

by the solvent recovery system is achieved since the cross-sectionalarea through which the fiowing evaporative medium passes is diminished,therebyincreasing the velocity of the evaporative medium acrossthevfilaments just prior to their exit from the cell enclosure. Byvarying the type of threat insert I l near l 2 the Venturi efiect may beVaried so that at .diiierent volumes of gas (evaporative medium) flow,which are required in spinningatdiiierent denyards, the linear velocityacross the thread and the suction effect at the thread outlet may besuitably varied. By changing the'size of the bafile or insert II thearea through which the gas flows can be changed to give whatever linearvelocity is desired. The desired restriction in the vent I B'may, ofcourse, be attained by shaping the 'yent as by indentations. It ispreferred, however, to use separate inserts, for the fluid flow can bevaried more at will using various inserts attached simply'as-shown inFigure 1. Further the inserts may be in other forms such as a barattached to thedooryfii. All that is needed is a passageway connectingth tapered end section to the vent which passageway is smaller than theend section and vent.

Still referring to Figure 1, the evaporative medium is led into the cellenclosure through one or more openings at the upper part of the cell(not shown) and is withdrawn through screen 53 which is placed in theassembly so as to be easily removable therefrom and then via conduit Mto the solvent recovery apparatus (not shown). Trap door [5 which ishinged at point I6 is maintained in its normal position by a retaininspring I? and may be readily opened as soon as any accumulation of yarn,broken filaments, etc. are observed therein. This permits cleaningof-the portion of the apparatus below the yarn exit point withoutinterrupting the Spinning operation.

Referring to Figure 2, the guide 9 consists .01", preferably, beveledcorners on the polished slot or aperture 1. While other types of guidesmay be used it is preferred to position the guide as close as possibleto the aperture. lhe slanting walls of 9, the flow of fluid in the unitacross the filament, and the suction efiects combine to keep thefilament in the valley of the aperture. Although the drawing showsapparatus designed for single thread-production, the invention mayreadily be adapted for double or multiple'thread manufacture. In Figure3, the exit door 8, riding on hinges l0, and the trap door I5 are shownin the open, non-operating positions. The screen I3 is detachable andserves as a fluff trap. The solvent recovery line I4 is curved upwardand to the right side of the cell but this line could be exit doorassembly may recommended.

agate-,5

be constructed of metal, such as iron, cast aluminum, or other materialsnot adversely affected by the volatileliquid to be recovered from thefilaments. If thread guides j 'Although for convenience the inventionhas been described for use in co-current dry spinnin processes, it isnot to be implied that the apparatus hereinafter claimed is designedsolely to cover the situation where the, evaporative medium is moving inthe direction of the filament flow, for

' the invention is also applicable ,to countercurrentdry spinningprocedures.

i lose acetate ,from

. In": the spinningof cell acetone solutions, the evaporative medium ispreferably air containing acetone picked up in the process and isintroduced by suitable aspiration at' a rate of from 11-18 cu. ft./p'erminute per. wind-up position. The necessary control of the rate ofpassage of the evaporative medium may .be secured with suitablefiowmeters and/or' orifices in a known fashion. The enclosuresurrounding the exit of the yarn may vary somewhatfrom that in the abovediscussed drawings. It is preferred, of course, that the enclosure havea smoothly curved assembly as shown rather than any angular contour,since stagnant corners are thereby avoided to a large extent. It isnecessary, however, to employ a. tapering type of arrangement in orderto create the desired suction. A thread guide may be positioned close tothe opening through which the filaments pass from the enclosure into theatmosphere.

With the present day emphasis onincreased spinning speeds, particularlyin the case of the dry-spinning of cellulose acetate yarn, the

greater has been the tendency, in heretofore known devices, for thesolvent-laden air to be dragged into the atmosphere. When usingconventional aspiration take-off devices and single thread cone doorsthe acetone concentration of the air being dragged from the cell at apoint 1" below the thread exit opening was about grams/cubic meter. Withthe design of the present invention the acetone concentration of the airat a point 1" below the thread exit opening was about 4 grams/ cubicmeter or about the same as the room average in the neighborhood asmeasured by a standard acetone meter. This indicates that a substantialreduction in the amount of solvent being carried into the spinning roomhas been achieved by the device of this invention. By reducing the crosssection at position I2in the cell enclosure, the velocity of theevaporative medium is increased with a resultant drop in pressure,thereby creating a suction (ca. 0.33 inch water vacuum) and permittingair to flow from the room into the cell through the aperture rather thanin the reverse direction, thereby minimizing solvent loss.

The invention is useful in the production of. any filaments, syntheticor natural. Although the apparatus has been described primarily inconnection with the dry-spinning of acetone-soluble cellulose acetatefrom an acetone solution, the invention is also applicable to thedry-spinning of cellulose acetate of the same or different combinedacetic acid content dissolved in any one or more of the well-knownvolatile solvents for cellulose acetate. Also, esters and ethers may bespun into yarn from a other cellulose organic 7 6 suitable solution ofvolatile solventsutilizingthe apparatus hereinafter claimed. Forinstance, yarns of cellulose propionate, cellulose butyrate, celluloseacetate propionate, cellulose acetate butyrate, etc. may beproduced. Theapparatus may also be used in conjunction with the manufacture of yarnsfrom condensation products of cellulose and glycols or other polyhydricalcohols or other-f materials that are capable of being formed intofilaments by evaporative or dryspinning methods. The volatile solventemployed in the above-mentioned cases may be any volatile one in whichsaid material is soluble, for example,

'methyl ethyl ketone, methyl alcohol, ethyl alcohol, ethylene glycol,methylene chloride, ethylene chloride, propylene chloride, methylacetate, ethyl acetate, ethyl lactate, ethyl alphahydroxybutyrate,dioxane, diacetone' alcohol, chloroform, tetrachloroethane or similarchlorinated hydrocarbons of mixtures thereof with small amounts ofalcohol. The device may also be used ,in the handling of other filamentssuch as those from polyamides, polyacrylonitriles,

polyvinylchlorides and the like. It may be readi- 1y, adapted for thehandling of yarns, wires, rods, tubing and, in general, of anycontinuous filamentary structure. The structure need not be freshlyformed. The apparatus may be used, for example, in removing water from apreformed filament. The device can be used, in general, for separating atraveling filament from a fluid.

The present invention has particular utility in preventing the loss ofsolvent from the cell enclosure through the aperture by which therapidly traveling yarn passes to the wind-up. Obviously the higher thespeed of the filament travel, the greater will be the percentage ofvolatile'solvent carried out intothe atmosphere, other conditionsremaining constant. By use of the apparatus hereinabove described high.speed spinning may be employed with minimum acetone losses.

'mum human exposure concentration of 4.84

grams/cubic meter (2,000 p. p. m. by volume) for a daily 8-hour exposureset by the American Standards Association Committee on Toxic Vapors,Dust and Gases.

The apparatus also has the advantage of being easily cleaned and ofbenefiting spinning by minimizing conditions causing filament breaks,

as for example, by improving thread alignment.

Thus, by the employment of this apparatus high speed spinning of yarn bythe dry-spinning process is made more economically feasible and yarns ofimproved quality are produced due to diminution of air turbulence withinthe spinning cell.

Any departure from the procedure described herein which conforms to theprinciples of the invention is intended to be included within the scopeof the claims below.

We claim:

1. Apparatus for separating a traveling filament from a fluid whichcomprises a hollow member having a tapered end section; in that sectionan exit for said filament; and a vent for the exit of said fiuidconnected to said section by a passageway containing a constriction sothat said passageway is smaller than said section and said vent.

.2. Apparatus for separating a traveling filament from a fluid whichcomprises a hollow cylindrical member having a tapered end section; inthat section an exit for said filament; and a .vent for said fluidconnected to saidsection by a passageway containing a constriction sothat said passageway is smaller than said section. and said vent. 7 v

3. Apparatus for separating a traveling filamentfrom a fluid whichcomprises a hol1ow,cylindrical member having a tapered end section;inthat section an exit for said filament in a plane parallel to the longaxis of said member; and a vent for theexit of said fluid connected tosaid section by a passageway containing a constriction so. that saidpassageway is smaller than saidsection and said vent. I

l. Apparatus for separating a traveling filament from a fluid whichcomprises a hollow, cy-

lindrical member havin a tapered end section;

a door opening into said section; in said section an exit'for saidfilament; and a vent for the containing a constriction so that saidpassageway is smaller than said section and said vent, said ventextending below said filament exit.

6. Apparatus for separating a traveling filament from a fluid whichcomprises a hollow, cylindrical member having a tapered end section; adoor opening into said section; in said section an .exit for saidfilament; a guide for said filament to said exit; and a vent for saidfluid connected to said section by a passageway containing aconstriction so that said passageway is smaller than said section andsaid vent, said vent extending below said filament exit; and a screen insaid vent.

7. Apparatus for separating a traveling filament from a fluid whichcomprises a hollow, cylindrical member having a tapered end section;

ardoor opening-into said section; insaid section an exit for saidfilament; a guide forsaid filament to saidexit; a vent for said fluidconnected to saidsection by a passageway containing a constrictionsothat said passageway in smaller than said sectionand said vent, saidvent extending below said filament exit; a screen in said vent; and anaccess in said vent to said screen.

8. Apparatus for separating .a traveling'filament from a fluidwhi'chcomprises a hollow member having a tapered end section; in that, sectionan exit for said filament; a vent for the exit of said fluidextendingbelow said filament exit; and a restriction in said vent contiguous withsaid. tapered. section for. enhancing the suction throughsaid filamentexit into said member.

9. Apparatus for separating a traveling cel- I luloseacetate filamentfrom an evaporating medium which comprises a hollow member having atapered end section; in that section an exit for said filament; a ventfor the exit of said evaporating medium; a passageway connecting saidvent to said tapered end section; in said passageway a constrictionmaking said passageway smaller than said section and said vent; a screenin said vent; a door opening into said tapered end. section; and anaccess in said vent to said screen.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 559,498 Scharrer May 5, 18961,722,797 Jessup July 30, 1929 2,341,615 Hofiman Feb. 15, 1944 2,403,416Vandegrifi" July 2, 1946 2,415,738 Freund Feb. 11, 1947 FOREIGN PATENTSNumber Country Date Italy Feb. 18, 1937

